<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
<title></title>
</head>

<body>
<img src="images/01.png" onmouseover="addBorder(event)" onmouseout="removeBorder(event)">
<script type="text/javascript">
    function addBorder(event){
        event.target.style.border = '1px solid green';
    }
    function removeBorder(event){
        event.target.style.border = 0;
    }
</script>
</body>
</html>
